Hello Max,
It seems you want to know SQLDataAdapter's implementation about how to read
back the added/updated row and update the related row. If I misunderstand,
please correct me. Thanks.
For Typed Dataset Wizard, after you entered Select SQL statement, it will
use SqlCommandBuilder to generate the insert/delete/update SQL statement,
and then create the SP_INSERT/SP_UPDATE for us. If you check the REFRESH
THE DATA TABLE option in Adavanced Option, the generated stored procedure
is also included a select statement which will return the modified datarow.
PROCEDURE SP_UPDATE
....
UPDATE [dbo].[Table_1] SET [c2] = @c2, [c3] = @c3 WHERE (([c1] =
@Original_c1) AND ((@IsNull_c2 = 1 AND [c2] IS NULL) OR ([c2] =
@Original_c2)) AND ((@IsNull_c3 = 1 AND [c3] IS NULL) OR ([c3] =
@Original_c3)));
SELECT c1, c2, c3 FROM Table_1 WHERE (c1 = @c1)
After executed the SP_INSERT/SP_UPDATE, you can notice the stored procedure
not only insert/update the row in the database, but also return a record
set which identify the changes in underlying database.
For SQLDataAdapter, its update method will check the RowState property of
each row. If it is modified, The SqlDataAdapter calls the ExecuteReader
method on the SqlCommand object stored in its UPDATECOMMAND property, and
it checks the RecordsAffected property of the resulting SqlDataReader to
determine whether to apply values from the SqlDataReader to the DataRow.
Then, if the SqlDataAdapter determines that submitting the pending change
in a DataRow succeeded, the SqlDataAdapter checks the SqlCommand's
UpdatedRowSource property to determine how (or whether) it should apply
values returned by the SqlCommand to the DataRow
UpdatedRowSource:
Both Tells the SqlCommand to fetch new data for the row using both the
first returned record and output parameters. This is the default.
FirstReturnedRecord Tells the SqlCommand to fetch new data for the row
through the first returned record.
None Tells the SqlCommand not to fetch new data for the row upon execution.
OutputParameters Tells the SqlCommand to fetch new data for the row using
output parameters.
In your case, the UpdatedRowSource property is BOTH(by default). The
SQLDataAdatper will check both OutputParamets and FirstReturnedRecord.
However, due to no output parameter in this case, SQLDataAdatper use
SQLDadaReader.Read() method to retrieve the Fist Returned Record and modify
the related filed in current updated row.
This behavior has been mentioned in book <Programming Microsoft? ADO.NET
2.0 Core Reference> by David Sceppa.
Chapter 11. Advanced Updating Scenarios
- Refreshing a Row After Submitting an Update
- - Using Batch Queries to Retrieve Data After You Submit an Update
Hope this helps. If you still have anything unclear, feel free to update
here. We're glad to assist you.
Sincerely,
Wen Yuan
Microsoft Online Community Support
==================================================
This posting is provided "AS IS" with no warranties, and confers no rights.
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